I was wondering if there is a way to override the native functionality of the lookup field in Salesforce and replace it with a visualforce page. The reason I'm trying to override this button is because when the user does a look up, the look up returns everybody with that name. What we want to return is a list of all the contacts by account for the contact being searched.
Here's what I'm trying to achieve:
When the user clicks the lookup button my visualforce page will launch and allow the user to see the account and all the contacts of that account.
Is this even possible? What other ways would you suggest going about this?
Here's a screen shot of what I'm trying to change:

Thanks for all your help!